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<br />Rio Blanco County Area, Colorado <br />and the more desirable forage plants have achieved <br />sufficient growth to withstand grazing pressure. <br />This map unit is in capability subclass Vlle, <br />nonirrigated. It is in Clayey Foothills range site. <br />32-Fluvaquents, frequently flooded. This map unit <br />is on alluvial valley floors and flood plains and in <br />oxbows, swales, and old river channels along major <br />rivers and streams. It formed in mixed alluvium derived <br />dominantly from sedimentary and basaltic material. Slope <br />is 0 to 3 percent. Areas are elongated and are 5 to 30 <br />acres. The native vegetation is mainly willows, water- <br />tolerant grasses, and some cottonwood trees. Cattails <br />are in some of the low-lying oxbows. Elevation is 5,100 <br />to 7,400 feet. The average annual precipitation is 8 to 20 <br />inches, the average annual air temperature is 38 to 50 <br />degrees F, and the average frost-free period is 45 to 120 <br />days. <br />These soils are deep and poorly drained. They consist <br />of thin layers of highly stratified clay loam to sand <br />underlain by very gravelly and cobbly sand. <br />Included in this unit are small areas of Redrob loam, <br />Redrob Variant loam, Colorow sandy loam, and <br />Trembles loam, wet. <br />Permeability is very rapid. Available water capacity is <br />moderate to high. The rooting depth is adequate to <br />support only water-tolerant vegetation. A seasonal high <br />water table fluctuates between depths of 6 and 36 <br />inches in spring and summer. Most of this unit is subject <br />to periods of flooding in spring. <br />Use of this unit is limited to some livestock grazing <br />after the periods of flooding in spring and to habitat for <br />some watertowl, muskrat, and beaver. <br />This map unit is in capability subclass Vllw. It is in <br />Riverbottom range site. <br />33-Forelle loam, 3 to 8 percent slopes. This deep, <br />well drained soil is on terraces and uplands. It farmed in <br />eolian and alluvial material derived dominantly from <br />sedimentary rock. Areas are irregular in shape and are <br />20 to 600 acres in size. The native vegetation is mainly <br />low shrubs and grasses. Elevation is 5,800 to 7,200 feet. <br />The average annual precipitation is 15 to 18 inches, the <br />average annual air temperature is 42 to 45 degrees F, <br />and the average frost-free period is 80 to 105 days. <br />Typically, the surface layer is pale brown loam 4 <br />inches thick. The upper 12 inches of the subsoil is <br />yellowish brown clay loam, and the lower 5 inches is <br />light yellowish brown loam. The substratum to a depth of <br />60 inches or more is very pale brown loam. <br />Included in this unit are small areas of Patent loam, <br />Piceance fine sandy loam, Work loam, Yamac loam, and <br />Zoltay clay loam. Included areas make up about 15 <br />percent of the total acreage. The percentage varies from <br />one area to another. <br />Permeability of this Forelle soil is moderate. Available <br />water capacity is high. Effective rooting depth is 60 <br />35 <br />inches or more. Runoff is medium, and the hazard of <br />water erosion is moderate. <br />Most areas of this unit are used for nonirrigated and <br />irrigated crops, livestock grazing, and wildlife habitat. A <br />few areas are used for urban development and as a <br />source of topsoil. <br />This unit is well suited to nonirrigated small grain and <br />irrigated hay and pasture. Wheat is the main nonirrigated <br />crop. <br />If this unit is used for small grain, the main limitations <br />are the hazard of erosion, a short growing season, and <br />low precipitation. Because precipitation is not sufficient <br />for annual cropping, a cropping system that includes <br />small grain and summer fallow is most suitable. <br />Maintaining crop residue on or near the surface <br />reduces runoff, reduces soil blowing, and helps to <br />maintain soil filth and organic matter content. Soil <br />blowing can also be reduced by keeping the soil rough <br />and cloddy when it is not protected by vegetation. On <br />long slopes, chiseling the stubble in fall slows runoff and <br />reduces soil loss in years when the snow melts rapidly <br />while the soil is still frozen. Chiseling also promotes <br />better aeration. <br />This unit is well suited to hay and pasture. The main <br />limitations are a short growing season, the hazard of <br />water erosion, and low precipitation. Use of nitrogen, <br />phosphorus, and manure fertilizer promotes good growth <br />of forage plants. Proper stocking rates, pasture rotation, <br />and restricted grazing during wet periods help to keep <br />the pasture in good condition and to protect the soil from <br />erosion. Irrigation water can be applied by the sprinkler, <br />corrugation, and controlled flooding methods. Leveling <br />helps to insure the uniform application of water, <br />The potential plant community on this unit is mainly <br />western wheatgrass, prairie junegrass, big sagebrush, <br />Douglas rabbitbrush, streambank wheatgrass, and <br />needleandthread. The production of forage is limited by <br />a short growing season and low precipitation. The <br />average annual production of air-dry vegetation is about <br />800 pounds per acre. <br />If the range is overgrazed, the proportion of preferred <br />forage plants decreases and the proportion of less <br />preferred forage plants increases. Therefore, livestock <br />grazing should be managed so that the desired balance <br />of preferred species is maintained in the plant <br />community. <br />Management practices suitable for use on this unit are <br />proper range use, deferred grazing, rotation grazing, and <br />brush management. If the range is in poor condition, <br />seeding is also a suitable practice where slopes are less <br />than 15 percent. For successful seeding, prepare a <br />seedbed and drill in the seed. The plants selected for <br />seeding should meet the seasonal requirements of <br />livestock or wildlife, or both. <br />If this unit is used for urban development, the main <br />limitations are low soil strength, the potential for <br />shrinking and swelling, and the hazard of frost action. <br />